We may have found other answers which could help you.
Click here for Singer Thread MachineSinger 507?
how to get the tension right on my machine?
My CG 500/550 Singer Sewing Machine's bobbin isn't working?
1965 Singer 275k sewing machine foot pedal?
What size needles can I use for my Singer 39a3?
Singer zigzag 457 Stylist not threading bobbin/making stitch?